Abstract:
In order to reveal the intrinsic relationship among soil microbial, enzyme activities and heavy metal contents in polluted soil, and to establish a characterization system between enzyme activities and biological parameters corresponding to different heavy metal pollution levels in soil, five different functional areas (mining area, concentrating area, heap area, tailings area and vegetable garden) in Tongling mining area of Anhui Province were studied. The heavy metal contents (Cu, Zn, Cd, Pb), microbial biomass carbon (MBC), basic respiration, metabolic quotient (qCO
2) and six soil enzyme activities (catalase, urease, alkaline phosphatase, neutral phosphatase, cellulase and sucrase) were measured. The results showed that the Nemerow comprehensive pollution index (
PN) of soil in different functional areas of the mining area was in the order of heap mining area (10.77) > mineral processing area (4.38) > mining area (4.06) > tailings area (2.55) > vegetable garden (1.35). The single factor pollution index (
Pi) of the heavy metals (Cu, Zn, Cd and Pb) was Cd > Cu > Zn > Pb. In addition, the activities of selected soil enzymes were significantly different in different functional areas, and the soil enzymes in the vegetable garden area were the most active. Catalase, neutral phosphatase and invertase activities could effectively characterize the levels of the heavy metal contents (Cu, Zn, Cd, Pb). Metabolic entropy is a better indicator of soil environmental pollution than soil basic respiration or microbial biomass carbon. Soil enzyme activities and metabolic entropy were significantly correlated with the contents of four heavy metals. Therefore, the biological parameters such as soil enzyme activities and metabolic quotient can provide a reference basis for environmental quality assessment and ecological restoration in mining areas.